1. Field of the Invention
The present invention relates to a parallel-plate type plasma etching electrode used in production of semiconductor integrated circuits (e.g. IC and LSIC) or guidewaves for optical communication, as well as to a process for production of the plasma etching electrode.
2. Description of the Related Art
As semiconductor integrated circuits are becoming increasingly finer and more dense, the technical requirements for a parallel-plate type plasma etching electrode capable of forming a fine pattern on a wafer at a high accuracy are becoming higher.
The plasma etching electrodes in current use are made of aluminum, graphite, glassy carbon, quartz, metallic silicon or the like.
These conventional plasma etching electrodes, however, wear during plasma etching and, moreover, react with an introduced gas to become an oxide or a fluoride and vaporize. This vaporization may badly affect a material to be etched (e.g. a semiconductor device) although the degree differs depending upon the material constituting the electrode or the purity of the material.
For example, aluminum, when it wears, generates its oxide which becomes a metal contamination source for material to be etched. Graphite, which is used as a sintered material, generates a large amount of dust during etching. Glassy carbon, although low in dust generation, has a limitation in purity and, further, contains a metal oxide which becomes a metal contamination source for material to be etched. Quartz, which originally has an insulating property, is not suitable for use as an electrode.
Meanwhile, metallic silicon, which is a material used for production of semiconductor, has an advantage that its impurities can be controlled to the same level as in semiconductor device, etc.
The conventional plasma etching electrode made of metallic silicon, however, generates dust because the microcracks presumed to be present on the electrode surface are destroyed by a plasma. Although the influence of this dust on material to be etched (semiconductor device, etc.) is thought to be small as compared with the cases using electrodes of other materials such as mentioned above, because the metallic silicon constituting the dust is the same material as used in the semiconductor device, etc., it is inevitable to avoid the contamination of the material to be etched, with the dopant contained in the dust.
Therefore, if there is developed a plasma etching electrode made of metallic silicon wherein the impurities are controlled to the same level as in semiconductor device, etc. and which generates no dust during plasma etching, it will greatly contribute to the development of a finer and more dense semiconductor integrated circuit.